1721641 has 4 divisors (see below), whose sum is σ = 1822932. Its totient is φ = 1620352.

The previous prime is 1721639. The next prime is 1721651. The reversal of 1721641 is 1461271.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1537600 + 184041 = 1240^2 + 429^2 .

It is a cyclic number.

It is not a de Polignac number, because 1721641 - 2¹ = 1721639 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1721651) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 50620 + ... + 50653.

It is an arithmetic number, because the mean of its divisors is an integer number (455733).

2^1721641 is an apocalyptic number.

It is an amenable number.

1721641 is a deficient number, since it is larger than the sum of its proper divisors (101291).

1721641 is a wasteful number, since it uses less digits than its factorization.

1721641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101290.

The product of its digits is 336, while the sum is 22.

The square root of 1721641 is about 1312.1131810938. The cubic root of 1721641 is about 119.8526199928.

The spelling of 1721641 in words is "one million, seven hundred twenty-one thousand, six hundred forty-one".